USB Matrix Switch System

ABSTRACT

An USB matrix switch system provided for a plurality of USB devices shared with a plurality of hosts is disclosed. The system comprises: (1) a plurality of DP PHYs, respectively, corresponding to the USB devices so as to transfer those series signal received from the USB devices to parallel signals; (2) a plurality of UP PHYs, respectively, corresponding to the hosts for transferring signal received therefrom to parallel signals or doing the reversal operation; (3) a plurality of hubs, respectively, corresponding to the UP PHYs, each hub has a digital repeater, a TT, an up router, a down router, and a hub controllers; (4) a signal fetching monitor for fetching a control signal provided by a user; (5) a plurality of signal control switch modules having a down stream port controller, a disconnection emulator, provided for simulating a disconnection status while the down stream port controller is empty, and a select MUX provided for switching a selected USB device to a selected hub in accordance with content of the hot key.

FIELD OF THE INVENTION

The present invention pertains to a USB matrix switch system, andparticularly to an USB matrix switch system for a plurality of hostscommon sharing resources of a plurality of USB devices.

DESCRIPTION OF THE PRIOR ART

As the external devices connected to the computer through the USB ports,it becomes easier and more convenient to use those expanded devices thanthrough a RS 232 series port or a parallel port for most of users.Whereas, if a plurality of hosts are desired to share common resourcesof a plurality of USB devices, the situation may become complexity.Since some of the USB devices are with high data transfer rate such ascard reader, high-grade scanner, which satisfy the specification of USB2.0 but some of the USB devices have only low/full data transfer ratesuch as keyboard and mouse.

According to USB 2.0 specification, the differential voltage is 3.3V forfull speed and/or low speed transfer rate, but it becomes 400 mV forhigh speed transfer rate. Such low voltage 0.4V is not enough to provideas a digital data, 0, or 1 judgment, in current manufacturing process ofapplication-specific integrated circuit (ASIC). It is thus complex todesign a matrix switch circuit or an advance manufacturing process ofASIC.

Referring to FIG. 1 a, it shows a conventional matrix switch system 50for m USB devices shared by n hosts. The switch system contains n hubsHUB1 to HUBn. Each USB device has a bus switch 30 corresponding thereto.The bus switch 30 itself is an analog type, which is demanded to haveprecise matched impedance and still exists some noise problemsespecially for high speed USB signal, it have to fine tune the impedancemore precise. Without precise impedance correction, the USB devicecompatible would be bad. Apart from that, the trace layout of the busswitches is complex and thus each bus switch itself is formed as a chip.Each hub is also a chip. It requires large area to mount the chips ofhubs and bus switches on a print circuit board (PCB).

Furthermore, since the voltages for high speed and for low/full speeddevices are different and the differential voltage is only 0.4V forformer USB device. It is thus in the matrix switch system for high speedUSB devices versus high speed hosts, the repeater 35 in the hub can onlybe an analog type. As is shown in FIG. 1B, it shows a schematicstructure of a conventional hub. In addition to an analog repeater 35,it comprises a down physical layer transceiver DP PHY, an up physicallayer transceiver UP PHY, and a transaction translator hereinaftercalled TT 40. TT 40 is a buffer device for those high speed hosts toaccess low and/or full speed USB device so as to avoid one of the low orfull speed USB device occupy the entire channel width. The workingvoltage of the TT is 3.3V. It is thus can be a digital type or an analogtype device.

As aforementioned descriptions in the background of the presentinvention, a conventional matrix switch system for m USB devices sharedby n hosts requires n hubs and m bus switches, which are an analog type.And the drawbacks include: high noise, precise impedance match, largelayout areas are often presented in the conventional switch system sothat the USB devices may have the compatible problems and large packagevolume.

SUMMARY OF THE INVENTION

In comparison with a digital device, an analog device is knownassociated with high noise. An object of the present invention is thusto provide an USB switch system integrated in an ASIC chip and operatedby digital signals. Accordingly, the ASIC chip can provide for aplurality of USB devices shared by a plurality of hosts. No matter theUSB devices are low speed keyboard, mouse, or high speed USB flash disk,or USB scanner. The signals running in the hub are all parallel signals.Both of the repeater and TT are all digital types so that they willprovide least noise and low layout area occupied in the integratedcircuit.

An USB matrix switch system provided for a plurality of USB devicesshared with a plurality of hosts is disclosed. The system comprises: (1)a plurality of DP PHYs, respectively, corresponding to the USB devicesso as to transfer those series signal received from the USB devices toparallel signals; (2) a plurality of UP PHYs, respectively,corresponding to the hosts for transferring signal received therefrom toparallel signals or doing the reversal operation; (3) a plurality ofhubs, respectively, corresponding to the UP PHYs, each hub has a digitalrepeater, a TT, an up router, a down router, and a hub controllers; (4)a signal fetching monitor for fetching a control signal provided by auser; (5) a plurality of signal control switch modules having a downstream port controller, a disconnection emulator, provided forsimulating a disconnection status while the down stream port controlleris empty; and a Select MUX provided for switching a selected USB deviceto a selected hub in accordance with content of said hot key.

In the preferred embodiment, for a high speed USB deice having data totransfer to a selected high speed host is through the digital repeater.Hence, the present invention solve the noise problem, precise impedancematched problem in accordance with the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

FIG. 1A shows a conventional USB matrix switch system according to theprior art.

FIG. 1B shows a hub having an analog repeater and TT according to theprior art.

FIG. 2A shows function blocks of an USB matrix switch system in an ASICchip according to a preferred embodiment of the present invention.

FIG. 2B shows a digital repeater and TT and the action thereof whilereceiving signals from upper level or from the down level according to apreferred embodiment of the present invention.

FIG. 2C shows a schematic diagram illustrating processes of out tokenand data followed through TT according to the present invention.

FIG. 2D shows an up router responding one among a repeater, TT, hubcontroller according to the present invention.

FIG. 2E shows a down router has m terminals for receiving parallelsignals from the repeater and TT according to the present invention.

FIG. 2F shows a down router have m terminals for receiving parallelsignals or disconnected signals from the down level according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As required, a detailed illustrative embodiment of the present inventionis disclosed herein. However, techniques, systems and operatingstructures in accordance with the present invention may be embodied in awide variety of forms and modes, some of which may be quite differentfrom those in the disclosed embodiment. Consequently, the specificstructural and functional details disclosed herein are merelyrepresentative, yet in that regard, they are deemed to afford the bestembodiment for purposes of disclosure and to provide a basis for theclaims herein, which define the scope of the present invention. Thefollowing presents a detailed description of the preferred embodiment(as well as some alternative embodiments) of the present invention.

The present invention provides a digital USB matrix switch systemintegrated in one ASIC chip. And the manufacture processes requires onlydeep-submicron process such as 0.18 μm.

To overcome the aforementioned problems, an USB matrix switch systemaccording to the present invention is disclosed, as is shown in FIG. 2A.In FIG. 2A, it shows the function blocks in the ASIC chip 100 for m USBdevices shared by n hosts from the bottom thereof comprising: (1) m downphysical layer receivers, DP PHY1 to DP PHYm, hereinafter called DP PHY,if it does not specially point out, one to one corresponds to the m USBdevices (not shown); (2) m signal control switch modules 105; (3) n hubsHUB1 to HUBn, hereinafter called HUB; (4) n upper physical layerreceivers, UP PHY1 to UP PHYn; and (5) a signal monitor 104 for fetchingthe command signal retrieved by hot key keyed in.

The DP PHY is to transfer series signals received to parallel signalssuch as USB transceiver macrocell interface (UTMI) parallel signals,random access memory (SRAM) signals or low pin count (LPC) parallelsignals. The DP PHY operates at different differential voltage inaccordance with the data transmitting rate. But the UTMI parallelsignals are operated at the same voltage, 3.3V. The DP PHY is totransfer parallel signals received from the correspondent USB device toseries signals and transmit the series signals to the correspondentsignal control switch module 105. The DP PHY is to transfer seriessignals received from the correspondent signal control switch module 105to parallel signals and transmit the parallel signals to thecorrespondent USB device. That is, each DP PHY is connected between aUSB device and a signal control switch module 105, and converts signalsbetween parallel signals and series signals. The UP PHY is to transferparallel signals received from the correspondent hub to series signalsand transmit the series signals to the correspondent host. The UP PHY isto transfer series signals received from the correspondent host toparallel signals and transmit the parallel signals to the correspondenthub. That is, each UP PHY is connected between a hub and a host, andconverts signals between parallel signals and series signals.

Each signal control switch module 105 includes a down stream portcontroller 105A, a disconnect emulator 105B, and a select multiplexer(MUX) 105C. The down stream port controller 105A is to receive theparallel signals from the lower level thereof, a corresponding DP PHY,and the select MUX 105C is to switch the parallel signals in the downstream port controller 105A to the target HUB in accordance with thecontrol signal 104A sent by the signal monitor 104. As no signals aredumped to the down stream port controller 105A, the disconnect emulator105B will be simulated to a status of disconnected with its lower end,e.g. no USB device. Each signal control switch module 105 connects thecorrespondent DP PHY to all hubs.

The monitor is installed to intercept the specified signals from the USBport and analyze the switch signals of the down stream thereto. Eachsignal control switch module may be arranged to have one monitor or allof the signal control switch modules have just one monitor to monitorthe intercept the specified signals from the USB port.

The disconnect emulator appended to the down stream port controller isto emulate the situation that the host and the unselected down streamport are disconnected while the corresponding USB device is unselectedaccording to the select Mux. The select signal is filed by the USER,which is then intercepted by the monitor(s) to determine which one ofthe hubs is selected and the selected hub will be connected to the realdown-stream port.

The select signal can be obtained by the two ways: one is received byexternal switch circuit. The other is intercepted by the monitor(s). Forinstance, the assigned down stream port pointed out the plug-in deviceis a HID KEYBOARD and the intercepted five signals are scroll, scroll,and 3 inserts and 1, the monitor(s) will assign the down stream port 3connected to 1.

Referring to FIG. 2B, the HUB includes an up router 118, a digitalrepeater 112, a transaction translator (TT) 114, a hub controller 116,and a down router 110. The detailed descriptions are as follows:comparing to the analog repeater provided with bypass function for highspeed USB to high speed host, the digital repeater 112 includes a firstqueue 112A and a second queue 112B. The first queue 112A is deviceretrieving signals from the up router 118 and transmitting them to theby down router 110 by a rule of first in first out. By contrast, thesecond queue 112B is a queue provided for parallel signals received fromthe down router 110 and transmitting them to the up router 118.

The TT 114 is provided for high speed host versus low and/or full speedUSB device to access signals to prevent the channel width from occupiedby a low and/or full speed USB device. Basically, the TT 114 includes afirst buffer 114A and a second buffer 114B. The first buffer 114A isprovided for high speed host from the up router transmitting data to thelow and/or full speed USB device through down router 110. The secondbuffer 114 b is provided for data from the low and/or full speed USBdevice through down router 110 to a high speed host through the upperrouter 118. Herein the high speed USB devices or hosts are pointed outthose devices or host whose data transmitting speed comply with thespecification of USB 2.0, 480 Mbps. The data transmitting speed for fullspeed is about 12 Mbps and the low speed device such as a keyboard or amouse, usually has data access rate by 1.5 Mbps.

The TT 114 (transaction translator) is designed according to the USB 2.0specification. While a high speed host accesses the signals from theperipheral USB device is a full/low speed type. The TT 114 provided asbuffers so that the full/low speed USB device will not occupy the wholechannel width of the high speed channel.

FIG. 2C is a schematic diagram illustrating processes of out token anddata followed through the TT 114. While a high speed host is prepared toaccess to a full/low speed USB device. The processes are as follows:firstly, the host sent a split start token to inform TT 114 of whichdown stream ports is the destination and the out token and the data willbe delivered thereto. The TT 114 then stores the out token and the datafollowed to the first buffer 114A. Thereafter, the out token and thedata in the first buffer 114A will be delivered to the DP by either fullor low speed transfer rate. During forgoing delivering time, the host isstill capable of accessing others e.g. high speed device or portswithout being interrupted or waited. After waiting a while, the hostwill send ‘split complete token” to TT 114 to inquire whether the dataare transferred completely. If the first buffer 114A is already empty,TT 114 will send ‘ACK” signal (acknowledge) responded by DP to the host,otherwise, a “NYET” signal (not yet) will be sent to host. The host willaccess to other high speed device and send ‘split complete TOKEN” again,as aforementioned, until the data are transferred completely.

The up router 118 includes an arbiter 118A, as is shown in the FIG. 2D.A request packet issued by a host will be transferred to parallelinterface signals firstly by the UP PHY corresponded and the parallelsignals are then duplicated to three copies and sent, respectively, tothe digital repeater 112, TT 114, and hub controller 116 by the uprouter 118. One and only one of them 112, 114, and 116 will respond tothe arbiter 118A. Those packets without response will be discarded. Theup router 118 will record the replier and then connect the UP PHY to thedown level device, i.e. the USB device through the digital repeater 112,TT 114 or hub controller 116.

When the up router 118 receives the up UTMI, it will duplicate threecopies and deliver to digital repeater 112, TT 114, and Hub controller,respectively. Only one of them will respond to up router 118. Hence, uprouter 118 will wait for a “TX REQ” signal (transmitting request) issuedby an USB device to the arbiter and then route the responded UTMI Txsignal to the UTMI of the up stream.

Referring to FIG. 2E, the schematic shows the parallel signals sent froman upper level through the down router 110. As aforementioneddescriptions, each down router 110 has m terminals or ports 1101 to 110m. The parallel signals sent by high speed host to the down level, theup router 118 will record the signal source coming from which host. Allterminals 1101 and 110 m in the down router 110 will receive signalscoming from both digital repeater 112 and TT 114, as is shown in FIG.2D. As the HUB is connected with a low and/or full speed USB device, thedown stream port controller 105A will inform the message of the USBdevice so that only those parallel signals through the TT 114 will besent to the down level. By contrast, as the device is a high speed USBdevice, the down router 110 will discard the content in the TT 114 andsend the content of the digital repeater 112 to the USB device.

Every device may receive the UTMI Tx signal from either a digitalrepeater 112 or a TT 114. The down router 110 will determine the devicefollowed which signal should be acquired by it in accordance with thestatus of the DP informed by DP controller 105A. For instance, thedevice 1 informs the down router 110 that the device 1 is a high speedone. Then the down router 110 will send the Tx signal from the digitalrepeater 112 to the device 1. Device n informs the down router that thedevice n is a LS/FS one. Then the down router 110 will send the Txsignal from the TT 114 to the device n, as showed in FIG. 2D.

Please refer to FIG. 2F, it shows parallel signals sent from a downlevel to the upper levels through down router 110. As the parallelsignals in the down stream port 110A is sent and switched to theselected HUB according to the signal monitor 114 detected. The downrouter 110 in the selected HUB will have a terminal records theconnected USB device, the other terminals without the USB device will besimulated to be at the status of disconnection by the disconnectemulator. Furthermore, no matter what kind of speed type of USB devicehas, the parallel signals at the terminal will be sent to the digitalrepeater arbiter 110A and the TT arbiter 110B.

While the down router 110 receives the UTMI Rx signal, it will send itto either the repeater arbiter 110A or the TT arbiter 110B in accordancewith the speed of the device. The arbiter, either the repeater arbiter110A or the TT arbiter 110B, which receives the REQ will up deliver theUTMI Rx.

As the USB device to be connected is a low and/or full speed, thedigital repeater arbiter 110A will discard the parallel signal but theTT arbiter 110B will send the parallel signals to the TT 114.

As the USB device to be connected is a high speed, the TT arbiter 110Bwill discard the parallel signals but the digital repeater arbiter 110Awill send the parallel signals to the digital repeater 112.

The benefits of the present invention are:

-   -   1. All the forging DP PHY, signal control switch module 105,        signal monitor 104, HUB, and UP PHY can be integrated in an ASIC        chip, so that the area occupied at the print circuit board is        small.    -   2. Since the signals operated in the ASIC are only parallel        signals, it is thus operated at a voltage of about 3.3V and thus        the repeater is a digital type. Low noise is anticipated.

As is understood by a person skilled in the art, the foregoing preferredembodiments of the present invention are illustrated of the presentinvention rather than limiting of the present invention. It is intendedto cover various modifications and similar arrangements included withinthe spirit and scope of the appended claims, the scope of which shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar structures.

1. An USB matrix switch system provided for a plurality of USB devicesshared with a plurality of hosts, comprising: a plurality of DP PHYs,one to one corresponding to the USB devices so as to transfer thoseseries signal received from the USB devices to parallel signals; aplurality of UP PHYs, one to one corresponding to the hosts; a pluralityof hubs, one to one corresponding to the UP PHYs, each the hub having adigital repeater, a TT, an up router, a down router, the down routerrecorded connection status with the USB devices or disconnection status;a signal fetching monitor for fetching a control signal provided byuser; and a plurality of signal control switch modules, one by onecorresponding to the DP PHYs, each signal control switch modulecomprising: a down stream port controller, a disconnection emulator,provided for simulating a disconnection status while the down streamport controller is empty, and a select MUX provided for a selected USBdevices switched to a selected hub of the hubs in accordance with thecontrol signal.
 2. The USB matrix switch system according to claim 1wherein each of the digital repeater comprises a first queue and asecond queue, the first queue receiving parallel signals from a side ofthe hosts corresponding and transmitting to a side of the USB devicesand the second queue receiving parallel signals from a side of the USBdevices with high speed corresponding and transmitting to a side of thehosts with high speed or full/low speed corresponding and transmittingto a side of the hosts with full/low speed.
 3. The USB matrix switchsystem according to claim 1 further comprises a hub controller.
 4. TheUSB matrix switch system according to claim 3 wherein the up router islocated atop level of each hub, furthermore, as an UP PHY correspondedhave parallel signals preferred to be down transmitting, the up routerwill duplicate three copies and transmitting to the digital repeater,the TT and the hub controller and waiting for response from one of therepeater, the TT and the hub controller.
 5. The USB matrix switch systemaccording to claim 3 wherein the up router comprises an arbiter fordetermining a replier choosing from the digital repeater, TT, and hubcontroller and connecting the replier with one of the UP PHYscorresponded.
 6. The USB matrix switch system according to claim 1wherein the down router has m terminals so as to record disconnectionstatus or connection status with the USB devices.
 7. The USB matrixswitch system according to claim 1 wherein all of the select MUXs arecoupled with the signal fetching monitor.
 8. The USB matrix switchsystem according to claim 1 wherein the DP PHYs, signal fetchingmonitor, signal control switch module, signal fetching monitor, signalcontrol switch modules hubs, UP PHYs are all integrated in an ASIC chip.9. The USB matrix switch system according to claim 1 wherein theparallel signals are UTMI interface signal or LPC parallel signals. 10.The USB matrix switch system according to claim 1 wherein the controlsignal is generated while the user press a hot key.
 11. An USB matrixswitch system having m USB devices provided for n hosts sharing, the USBmatrix switch system comprising: m signal control switch modules, eachhaving a select MUX, a down stream port, and a disconnect emulator; mDN-PHYs to receive series signals from the m USB devices, respectivelyand to output parallels signals to the down stream port; a signalfetching monitor provided for receiving a control signal from an user; nhubs, each having a down router, a digital repeater, a TT, a hubcontroller, and an up router so that the parallel signals in one of thedown stream ports will be switched to down router of a selected hub bythe select MUXs according to the control signal received, and throughone of the digital repeater, and the TT to the up router; and n UP-PHYsto receive the parallel signals from the n hubs and output the seriessignals to the n hosts, and to receive series signals from the n hostsand output parallel signals to the n hubs, where n, and m are naturalnumber.
 12. The USB matrix switch system according to claim 11 whereineach of the digital repeater comprises a first queue and a second queue,the first queue receiving parallel signals from a side of the hostscorresponding and transmitting to a side of the USB devices and thesecond queue receiving parallel signals from a side of the USB devicescorresponding and transmitting to a side of the hosts.
 13. The USBmatrix switch system according to claim 11 wherein the up routercomprises an arbiter for determining a replier choosing from the digitalrepeater, TT, and hub controller and connect the replier with one of theUP PHYs corresponded.
 14. The USB matrix switch system according toclaim 11 wherein the down router has m terminals so as to recorddisconnection status or connection status with the USB devices.
 15. TheUSB matrix switch system according to claim 11 wherein the parallelsignals are UTMI interface signal or LPC parallel signals.